The final quest is starting to take shape

I did all the map building and the related picture hunting. I think I got the right ideas to make things interesting in the first part, which will involve sneaking into the enemy's lair (or go in guns blazing, and having to deal with some extra fights).

I am unsure if I want to have some sort of "heist planning" before the mission, though, as I would like to have the players do some intel gathering, and having to take some decisions on where to focus on, but due to the nature of the plot and the situation (I want to let players free to do whatever they want before they decide to embark on the final quest, so they can take their time and finish all the side quests, if they want to, and they have enough mental resistance to survive the journeys), I am unsure what element would limit the possibility to "scan" the location before you go in (maybe fear of being noticed if you do it too many times?). Having this choice would allow for slightly different starting points, or different scenarios and solutions based on it, which I think would help replayability.